Open Access
CMYK
Hist. Geo Space Sci., 2, 99–112, 2011
www.hist-geo-space-sci.net/2/99/2011/
doi:10.5194/hgss-2-99-2011
© Author(s) 2011. CC Attribution 3.0 License.
History of
Geo- and Space
Sciences
Advances in
Science & Research
Open Access Proceedings
Roald Amundsen’s contributions to our knowledge
of the
magnetic fields of the Earth and the Sun Drinking Water
A. Egeland1 and C. S. Deehr2
Engineering and Science
Open Access
Department of Physics, University of Oslo, P.O. Box 1048, Blindern, 0316 Oslo, Norway
The Geophysical Institute, University of Alaska Fairbanks, 903 Koyukuk Ave., Fairbanks, Alaska 99775, USA
1
2
Open Access
Received: 29 August 2011 – Revised: 31 October 2011 – Accepted: 8 November 2011 – Published: 10 December 2011
Earth System
Science
Abstract. Roald Amundsen (1872–1928) was known as one of the premier polar explorers in the golden age
Data
Open Access
of polar exploration. His accomplishments clearly document that he has contributed to knowledge in fields as
diverse as ethnography, meteorology and geophysics. In this paper we will concentrate on his studies of the
Earth’s magnetic field. With his unique observations at the polar station Gjøahavn (geographic coordinates
68◦ 370 1000 N; 95◦ 530 2500 W), Amundsen was first to demonstrate, without doubt, that the north magnetic dippole does not have a permanent location, but steadily moves its position in a regular manner. In addition, his
carefully calibrated measurements at high latitudes were the first and only observations of the Earth’s magnetic
field in the polar regions for decades until modern polar observatories were established. After a short review
of earlier measurements of the geomagnetic field, we tabulate the facts regarding his measurements at the
observatories and the eight field stations associated with the Gjøa expedition. The quality of his magnetic
observations may be seen to be equal to that of the late 20th century observations by subjecting them to
analytical techniques showing the newly discovered relationship between the diurnal variation of high latitude
magnetic observations and the direction of the horizontal component of the interplanetary magnetic field (IMF
By ). Indeed, the observations at Gjøahavn offer a glimpse of the character of the solar wind 50 yr before it was
known to exist. Our motivation for this paper is to illuminate the contributions of Amundsen as a scientist and
to celebrate his attainment of the South Pole as an explorer 100 yr ago.
1
A brief biography
Roald Egelbregt Gravning Amundsen was born near Oslo,
on 16 July 1872 and he disappeared on 18 June 1928 while
on an airborne rescue mission somewhere in the Norwegian
Sea. As the fourth son in a maritime family, his mother was
anxious for him to become a physician. He studied along this
line until the age of 21, when his mother died, and he ran to
his life’s dream of polar exploration. To this end, he became
perhaps the pre-eminent polar explorer, having sailed, flown,
or skied to the north and south geographic poles, the north
magnetic dip pole, and through the northwest and northeast
passages.
After receiving his Captain’s papers, Amundsen set his
sights on the Northwest Passage with the idea that exploration was a scientific enterprise. It is clear from the contemporary and later analysis and publication of the scientific
Correspondence to: A. Egeland
([email protected])
Published by Copernicus Publications.
Social
Geography
results that Amundsen contributed significantly to the emergence of Norway as a dominant nation in polar meteorology,
geophysics, cosmic physics and even ethnography. His entrepreneurial style of exploration extended to his scientific
efforts as well. Here we will concentrate on his contributions
to the study of geomagnetism, mainly during the 1903–1906
expedition through the Northwest Passage (see e.g. Huntford,
1987).
Amundsen was fascinated by the invisible magnetic field,
and learned early on that a compass was important for orientation and navigation, particularly out at sea. During the
Belgica expedition, 1897–1999, on which he sailed as first
mate, he followed with interest the magnetic observations
that were carried out. In his diary on Monday 15 August
1898, he wrote that he and two other crew members were
planning to locate the magnetic pole in Antarctica (Kløver,
2009). Unfortunately, that trip was not carried out.
Amundsen started preparation for the Northwest Passage
expedition by proposing to locate the north magnetic dip
pole (NMDP) (Fig. 1). His background knowledge in geomagnetism was limited. Shortly after he was back from the
559 Figure One
560 100
A. Egeland and C. S. Deehr: Roald Amundsen’s contributions to our knowledge
Figure 1. Amundsen’s Gjøa expedition received much attention in
the international media (from The Los Angeles Times, 1906).
Belgica expedition, he started a more serious education in
geomagnetism, both theoretical and observational, before he
bought the Gjøa vessel, in 1901. The first scientist to whom
Amundsen mentioned his plan to locate the NMDP was the
Deputy-Director of the Norwegian Meteorological Institute
in Oslo, Dr. Axel S. Steen, who at once became interested
(Steen et al., 1933).
Armed with an introduction from Dr. Nansen, he soon
made his way to the Director of Deutsche Seewarte near
Hamburg, where his goal of geomagnetic studies and locating the NMDP was met with enthusiastic support by Director
Georg von Neumayer. Amundsen, together with the Gjøa
crew member Gustaf Wiik, spent several months in 1902
and 1903 at the Deutsche Seewarte Institute and at the Magnetic Observatory in Potsdam, near Berlin. Professor Georg
von Neumayer and Professor Adolf Schmidt helped considerably both in planning the magnetic observations and ordering the best instruments (cf. Schröder et al., 2010). However,
Dr. Steen was his main scientific guide. Mr. Wiik (1887–
1906) was an unusually dedicated worker, the fact of which
is clearly demonstrated by inspection of all the magnetic
recordings from the expedition. Extreme temperatures and
stormy weather never stopped him from his daily routine of
the magnetic observations. The goals of the Gjøa expedition
was the subject of news reports in many national and international newspapers as the headline from the Los Angeles
Times in Fig. 1 illustrates.
2
Geomagnetism – a brief introduction
Magnetic fields are a fascinating subject, and the most mysterious of the force fields we experience every day. Only
by long-term measurements of the Earth’s magnetic field at
many observatories can we acquire knowledge about the internal field characteristics. In addition, the changes in the
field intensity and direction at individual stations reveals
facts about the electric currents in the upper atmosphere, the
local geology and the solar activity responsible for the external field variations at that station. These parameters are
introduced to models of the internal (geomagnetic) field that
are calculated to provide geomagnetic latitude and longitude
coordinates for the Earth. Thus, the model geomagnetic field
at any point on Earth (including the pole) will not actually
correspond to observations of the field at that point, but it
Hist. Geo Space Sci., 2, 99–112, 2011
will place the station in the context of the total internal geomagnetic field.
The earliest recorded evidence of measurement of the
Earth’s magnetic field is connected with the direction-finding
capability of the compass, and that is dated to the eleventh
century in Chinese history (cf. The Encyclopaedist ShonKau, AD 1030–1093), while other sources claim that Chinese had knowledge of the compass two thousand years
before Christ. In European literature, the earliest mention
of the compass and its application to navigation appeared
in two works by Alexander Neekan, a monk at St. Albans
(AD 1157–1217). It is mentioned that the “mariners used
that means to find their course when the sky was cloudy”.
The directive properties of the magnets are a reliable direction finder in dark and cloudy weather. Therefore, the geomagnetic field has been linked to navigation for years. Petrus
Peregrinus, a French engineer, described the first real experiments in Europe with lodestones in 1269 (Brown, 1949). By
the fourteenth century, many sailing ships carried compasses.
That the direction to magnetic north, relative to geographic
north, differs over most of the globe had also been known for
a long time. The difference is called magnetic declination. A
more detailed history can be found in the paper: Follow the
needle: seeking the magnetic poles, by Good (1991; see also
Silverman and Smith, 1994). Chapter XXVI in Chapman and
Bartels (1940) monumental work on geomagnetism includes
an early history of geomagnetism.
More than 400 yr ago, it was demonstrated that the Earth
itself is a giant magnet (Gilbert, 1600, 1958). The Earth’s
magnetic field is also called the geomagnetic field. To the
first approximation the geomagnetic field has a dipole form,
with a north and a south pole located near, but not aligned
with the south and the north geographic poles, respectively
(see Fig. 2). Due to the strong dipolar character, the shielding effect against charged cosmic and solar wind particles is
weakest in the polar regions because of the open field lines.
There are variations in the main field, resulting in movements
of the poles, polar reversals, and changes in the strength of
the field. These usually occur over periods of time longer
than a year, and are called secular variations. At any single
location on Earth, variations in observations of the main field
occur on shorter time scales and are due to local ionospheric
currents, the local geology and solar activity.
3
Locating the north magnetic dip pole (NMDP)
before 1900
Before 1900, changes in the position of the north magnetic
pole were thought to be important for new sailing routes, particularly from Europe to Asia. Therefore, its location had
raised public interest because many people thought (and still
do) that compasses point to the pole, despite evidence that
the needle is responding only to the local magnetic field.
Models of the geomagnetic field differ in detail from the
www.hist-geo-space-sci.net/2/99/2011/
18
A. Egeland and C. S. Deehr: Roald Amundsen’s contributions to our knowledge
561 101
Figure Two
562 Figure 2. The figure illustrates a simple model of the Earth’s magnetic field in a plane. It is assumed that the field is due to a magnetic dipole
located in the centre of the Earth. The dotted line, which makes an angle of ∼11◦ with the geographic axis, is called the dipole axis, and
where it intersects with the surface of the Earth, the field is hypothetically vertical. The point where the horizontal component is zero, the
vertical component is a maximum and the inclination, or dip is 90 degrees, is called the North Magnetic Dip Pole (NMDP). The latitude is
measured from the equator. The magnetic elements, the horizontal component
H, the vertical component Z, the north component, X, the east
component Y, the declination D, and the inclination I are marked. The field has the direction as indicated by the arrows. Thus, the Earth’s
magnetic field is positive pointing downward toward the Northern Hemisphere, and the dipole pole in the Northern Hemisphere is a south
563 Figure
pole. Because opposites attract, the south dipole pole attracts the
north pole
of a Three
compass.
564 565 measurement of the magnetic field at any point on the Earth.
Because each model or representation of the field has a pole
at different locations, there is still confusion over the meaning and location of the magnetic pole. However, the only
pole that can be directly measured, is the dip pole, called
the NMDP. This is the point on the Earth where the horizontal magnetic component is zero and where the vertical component is maximum; thus it is the spot where a magnetized
needle would stand vertically to the Earth’s surface; i.e. the
inclination is 90◦ . The search for the NMDP began in earnest
around 1800 with the British Royal Navy’s campaign to discover the Northwest Passage. Because the NMDP is located
where the climate is so extreme and so remotely from where
people are living, the task to locate its position was difficult.
James Clark Ross (cf. Commander John Ross’s 1835
monograph and lecture at The Royal Society, December
1833, Ross, 1834) reported his magnetic observations during
the Victory expedition on the west coast of Boothia Peninsula
(Fig. 3). Measurements of NMDP were made by a dip circle
instrument, which was a sort of a vertical compass. James
Ross measured an inclination of 89◦ 590 with his dip circle
instrument on 1 June 1831. For all practical purposes, he had
found the NMDP. The geographic coordinates for the pole
were revised by Nippoldt (Nippoldt, 1929) to 70◦ 050 north
(N) and 96◦ 460 west (W).
It was suggested by Ross, that the magnetic pole had
an area of about 50 miles in diameter, for which there
was no apparent horizontal force (1 statute mile = 1.852 km).
Ross’s dip circle readings were given for noon, 03:00 p.m.,
www.hist-geo-space-sci.net/2/99/2011/
Figure 3. A drawing showing James Clark and co-workers locating
the North Magnetic Dip Pole in 1831 (from Ross, 1835).
05:00 p.m. and 07:00 p.m., i.e. four observations. The final
value given is the mean of all his readings. The results were
variable, which he could not explain. With a simple dip circle
instrument, it is difficult to determine accurately the position
of the pole. James Ross did not claim to have stood on the
very spot of the magnetic pole, but thought he was within a
mile or so of the pole. Unfortunately, he did not know that
even on a magnetic relatively quiet day, the pole he tried hard
to locate can change by about 5 km in one hour.
Hist. Geo Space Sci., 2, 99–112, 2011
102
A. Egeland and C. S. Deehr: Roald Amundsen’s contributions to our knowledge
Table 1. For the various magnetic measurements, the Expedition was provided with these instruments. The Reference Name is how the
instrument is referred to in the data lists. Units 6, 7 and 8 were recording instruments (see Steen et al., 1933).
566 567 568 Figure Four
No.
Instrument
S/N
Reference Name
1
2
3
4
5
6
7
8
9
10
Theodolite Zschau
Theodolite Seeman
Inclinatorium Dover
The Fox-circle
Earth-Inductor, Toepfer
Eschenhagen variometer
Eschenhagen variometer
Eschenhagen variometer
5 chronometers, plus two pocket models
Six thermometers
289
219
154
21
Z.
S.
Dover.
Fox.
E. I.
D
H
Z
Figure 4. The magnetometer hut at Gjøahavn. The hut was built
from shipping cases and non-ferrous metals, it was covered to keep
out light and cold. Amundsen suffered CO poisoning to his heart
muscle when he remained too long inside, tending the magnetometer (from Steen et al., 1933).
4
Roald Amundsen’s measurements of the magnetic
field at Gjøahavn
On 1 March 1903 the Gjøa Expedition sailed out of Oslo
harbor. The preparation and care with which Amundsen approached the polar magnetic studies for the Gjøa Expedition,
were unprecedented. Because most previous explorers were
constantly moving, there were only point measurements of
the field at different places, which gave no indication of the
local variations with time. Amundsen followed the advice of
experts and established a permanent station approximately
200 km from the assumed position of the pole and made continuous observations for almost two years. His studies were,
no doubt, sparked by the location of the Magnetic Pole near
the route of the Northwest Passage. The main purpose was to
explore the region and “to determine the present geographical coordinates of the magnetic pole-point”.
The magnetic instruments and accessories are listed in Table 1. Altogether three magnetic instruments were chosen
with great care in Germany, two were purchased in England,
while three were borrowed from the Norwegian Meteorolog Hist.
Geo Space Sci., 2, 99–112, 2011
20
A, B, C, D and E, No.7 and 8
I, II, 4, 5, 6 and 898
ical Office and from Professor Kr. Birkeland at the University
of Oslo. The most important instruments were the standard
variographs for the continuous recording of the field. In addition, they had three instruments – inclinatoria, for determine the inclination angle. For recording declination they
had two instruments. Some instruments were especially constructed for field observations close to the pole, where the Hcomponent is small while Z is large (cf. Steen et al., 1933).
The survey to locate the magnetic pole is in principle similar to a magnetic survey of any other region. However, the
climate at the remote location of the magnetic pole imposed
several practical constraints. The characteristic properties of
the Earth’s main field, and its changes, are difficult to measure from one station, and impossible to map accurately by
observing over a short period. This is because there are
many different contributions to the main geomagnetic field
and they are variable.
The permanent magnetic station (Fig. 4) was built by
Amundsen and his crew at Petersen bay, on King William
Land and was called Gjøahavn. Gjøahavn was well into the
polar cap and estimated to be within 200 km of the NMDP,
shown on the map in Fig. 5. The observations were going
day and night, without interruption for more than a year and
a half. In addition, absolute calibrations were made regularly (Fig. 6). Thus, about 360 absolute measurements of the
magnetic elements were carried out. Figure 7 shows the first
routine magnetograms from the three variometers for H, D,
and Z.
Eight magnetic field stations, four in the neighbourhood of
Gjøahavn, numbered 1, 2, 3 and 4, and four farther away at
Boothia Felix, where Ross had reported the location of the
pole, called I, II, III and IV, were operated. Their locations
(coordinates) are shown in Table 2. Short periodic observations were carried out at the field stations in 1904 and 1905.
The average values for the different magnetic elements, as
well as the estimated distances to the magnetic pole (d) from
the stations are also shown in Table 2 (Wasserfall, 1939).
www.hist-geo-space-sci.net/2/99/2011/
569 570 571 Figure Five
Figure Six
A. Egeland and C. S. Deehr: Roald Amundsen’s contributions to our knowledge
572 573 574 575 576 577 103
Figure 6. Amundsen making an absolute magnetic measurement
during the Maud expedition through the northeast passage (from
Amundsen’s archives at The FRAM Museum).
Figure 5. A map of the Canadian archipelago containing the
Boothia Peninsula and King William Land. Gjøahavn, the NMDPs,
and the temporary magnetic observatories listed in Table 2 are
shown.
Amundsen’s interest in geomagnetism dominated the scientific efforts during the three years spent on the way through
the Northwest Passage. Two over-winterings with magnetic
observatories made the data from the expedition unique. On
13 August 1905 they sailed out of Gjøahavn. They stopped in
Sitka, Alaska to intercalibrate the magnetic instruments with
the magnetometer established there. There Amundsen met
Harry Edmonds, who worked for Louis A. Bauer, a driving
force in Washington, DC for the improvement of magnetic
observations worldwide. Bauer was interested in the magnetic data, and offered to reduce and prepare them for publication. Amundsen, however, felt obligated to have this work
carried out in Norway (Silverman and Smith, 1994).
Around 1900, knowledge about geomagnetism was still
an emerging science. The expedition was carried through
during sunspot cycle 14. The monthly average number of
www.hist-geo-space-sci.net/2/99/2011/
sunspots was near 30 in 1903, but increased to 60 in 1905.
Thus, the expedition was carried out during moderately disturbed solar activity. Even if it is difficult today to evaluate
the magnetic observations, the recordings indicate high quality.
Amundsen himself has not carried out any detailed analyses of the observations. His few results are published in
The Northwest Passage (1908a) and in his lecture at The
Royal Geographic Society, on 11 February 1907 (Amundsen, 1908b). He appointed a committee consisting of Aksel
S. Steen, Deputy Director at The Norwegian Meteorogical
Institute, as chairman, while K. F. Wasserfall, at The Magnetic Byrå in Bergen and meteorologist N. Russeltvedt were
the other two members. Particularly Wasserfall had education and experience in geomagnetic studies. The editing of
the magnetic observations was not completed before 1932
(Steen et al., 1933). The most complete examination was carried out by Wasserfall in his 1938 and 1939 papers (Wasserfall, 1938, 1939).
An inspection of the magnetic records shows:
1. The average Gjøahavn magnetic values for the 19
months were: H = 760 ± 100 nT, D = 5.0◦ ± 3◦ and
I = 89◦ 170 1800 ± 60 . Changes in direction and intensity
were large and variable on time scales from minutes to
months.
2. A yearly variation with a significant maximum intensity
during the summer months is noted (cf. Fig. 8). Other
regular periodic variations can not be seen directly,
Hist. Geo Space Sci., 2, 99–112, 2011
580 104
A. Egeland and C. S. Deehr: Roald Amundsen’s contributions to our knowledge
Figure 7. Showing the first routine recordings of magnetic components H, D, and Z at Gjøahavn (from Steen et al., 1930). Imagine
Amundsen’s surprise when the newly-installed Gjøahavn magnetometers recorded one of the largest magnetic storms ever recorded on
31 October 1903 the first day they started the routine measurements (Cliver and Svalgaard, 2007).
Table 2. The nine magnetic observation sites, with geographic coordinates, average values for the magnetic elements, declination (D),
horizontal component (H) and inclination (I), are listed. The last column shows the estimated distance to the NMDP. Beechey Island was a
station on the route to Gjøahavn.
Station
Beechey Island
Gjöahavn
1.
2.
3.
4.
I.
II.
III.
IV.
φ
λ
74◦ 430 N
68◦ 370 N
68◦ 270 N
68◦ 280 N
68◦ 420 N
68◦ 480 N
69◦ 240 N
70◦ 250 N
70◦ 420 N
70◦ 560 N
91◦ 540 W
95◦ 530 W
95◦ 490 W
96◦ 180 W
95◦ 310 W
95◦ 560 W
95◦ 220 W
96◦ 180 W
96◦ 150 W
96◦ 210 W
except – during some of the months, a periodic variation of ∼28 days.
3. The largest sunspot maximum appeared between 22 August and 2 September 1904, “but it did not generate any
intense magnetic disturbances”. Wasserfall (1939) concluded that the sunspot curve and the magnetic observations for 1904 do not seem to show any general similarity.
The regular diurnal variation in the H-component, called
the Sq variations, is marked during all quiet days. Wasserfall (1927, 1939) also mentioned a period of ∼3 days, or 80 h,
both in the H and the sunspot data, but they are not shown
here.
The periodicity of polar magnetic storms in relation to the
solar rotation is of considerable interest. Based on a lot of
observations – mainly at low and medium latitudes, a significant period of nearly 27.3 days, the same as the rotation
period of the Sun, has been found (Chapman and Bartels,
1940). However, Amundsen’s magnetic data from Gjøahavn
show a period of 28.3 days (Wasserfall, 1927 and Fig. 9).
Hist. Geo Space Sci., 2, 99–112, 2011
D
H (nT)
128◦ 280 W
7◦ 240 W
44◦ 000 E
2◦ 500 E
35◦ 150 E
4◦ 100 W
35◦ 300 W
45◦ 400 E
120◦ 000 E
101◦ 300 W
1550
761
755
900
645
655
410
395
140
285
I
88◦ 20.00
89◦ 17.40
89◦ 15.00
89◦ 36.00
89◦ 34.00
89◦ 52.00
89◦ 38.00
d (km)
480
206
229
224
203
190
130
16
23
45
For comparison, Professor Birkeland, based on magnetic
observations from four high latitude stations during the winter 1902–1903 and from the first International Polar Year
1882–1983, found a period close to 29 days. “Regarding the
connection between sun-spots and magnetic storms it seems
improbably that the sun-spots can be the direct cause of
magnetic storms”, Birkeland concluded (Egeland and Leer,
1973). This periodicity is generally diminished during high
solar activity.
Regarding a 14-day periodicity, Birkeland’s terrella (as a
cathode) simulations of the Sun are of interest (Egeland and
Burke, 2005). When the charge was sufficiently strong, the
rays had a remarkable tendency to concentrate about two
spots diametrically opposite to each other, 14 days apart.
Both the 28- and the 14-day periodicity are fairly well
marked in 1904 data, but the 14-day periodicity is not detected every month (Wasserfall, 1927 and Fig. 10).
The longitudinal distributions of sunspots had a tendency
to concentrate along two meridians which have an inter distance of about 180 degrees on the Sun’s surface. This
www.hist-geo-space-sci.net/2/99/2011/
581 582 583 24
Figure Eight
A. Egeland and C. S. Deehr: Roald Amundsen’s contributions to our knowledge
105
Figure 8. The average daily intensity in nT (vertical scale) of the horizontal component at Gjøahavn from 1 November 1903 to 1 June 1905,
is shown. Notice that the variation from day to day is irregular and large; i.e. about 20 %. Furthermore, the seasonal variation shows a marked
minimum in the winter months. The oscillations in the daily variations during the summer months are largest. February, March and April
1905 is significantly more disturbed then the same period in the preceding year (from Wasserfall, 1938).
Figure 9. The
mean duration of the oscillations in the H-component at Gjøahavn for the year 1904 is 28.3 days. The vertical scale
26 is in nT
while the months – given by their number, is listed above. This curve shows that the 28.3-day period is maximum during equinoxes. From
October to December this period is very weak (from Wasserfall, 1927).
589 590 591 Figure Ten
592 Figure 10. This figure illustrates the 14-day period – actually the period is 14.3 days, for the horizontal component for year 1904. This
period is most marked from March to September (from Wasserfall, 1927).
www.hist-geo-space-sci.net/2/99/2011/
Hist. Geo Space Sci., 2, 99–112, 2011
106
593 27
Figure Eleven
A. Egeland and
594 C. S. Deehr: Roald Amundsen’s contributions to our knowledge
595 596 points from
597 the
598 pecould cause
599 peculiarity was one of the most important
Gjøahavn results. Thus, the Sun’s rotations
riodicities of both 14 and 28 days in the Earth’s polar atmosphere and in terrestrial magnetism. What Wasserfall could
not have known was that the relationship to multiples of the
solar rotation period was not connected to sunspots but to
high speed streams of solar wind particles from regions of
the solar corona called coronal holes. These were not discovered until X-ray pictures of the Sun from spacecraft showed
them as dark patches on the Sun, stable for as many as six
to ten solar rotations, producing magnetic effects on Earth at
regular multiples of the solar rotation (Zhang et al., 2005)
5
The position of the pole
The location of the north magnetic dip pole was an important goal of the Amundsen expedition. In the age of sail,
when the compass was one of the most important navigational instruments, it was regarded as a legitimate research
objective, even though it is of little interest to contemporary
scientific studies of the Earth’s magnetic field. “Unfortunately, the place on the Earth where the magnetic field is
vertical, is neither the magnetic pole nor a geophysically important location” Campbell (2003) concludes in response to
recent attempts to locate the NMDP.
For Amundsen it was important to find out if the pole
had moved since the Victory expedition. For weeks during
1904, Amundsen and co-workers were hunting for the Pole,
but could not pinpoint its position. A few times, they believed they were at its new position, but when they the following day carried out a double check, the dip needle swung
far off, indicating that the dip pole now was located farther
away. They concluded that the Pole had moved considerably
farther northward, between 1831 and 1904. Amundsen dis- covered that the NMDP “has not an immovable and stationary situation, but, in all probability, is in continual movement” (Amundsen, 1908a). This was a significant result of
Amundsen’s scientific studies of geomagnetism. He was disappointed because he wrote in his diary: “Our journey was
not a brilliant success”. He thought he had failed to attain
one of his goals.
The geographic coordinates of the Pole as listed by
Amundsen in 1904 were 70◦ 300 N and 96◦ 300 W (Amundsen, 1908b). The coordinates reported by Amundsen, were
changed by Wasserfall in 1939 to 70◦ 380 N, and 96◦ 420 W.
These values probably represent the best obtainable. Accepting these values, the average velocity of the north magnetic
pole from 1831 to 1904 has been a couple of km per year
in a northward direction. The next determination of the pole
position was carried out by the Canada government scientists
shortly after World War II. Changes in the pole position since
1590 is recently discussed by Korte and Mandea (Korte and
Mandea, 2008).
In preparation for the expedition, Prof. Schmidt advised
Amundsen to locate the permanent observatory at some
Hist. Geo Space Sci., 2, 99–112, 2011
Figure 11. The nearly elliptical curve shows the average diurnal
variation of NMDP, observed from Gjøahavn, in 1904. During quiet
conditions, the NMDP drifted 10–15 km, while during the summer
the drift was typically twice these values (from Graarud and Russeltvedt, 1926).
distance from the suspected location of the pole. He then set
out the following values for the magnetic elements in the
vicinity of the pole:
Vertical intensity Z = 62 000 nT
Inclination I = 90◦ − 0.50 a, at a distance of a miles
from the pole.
Horizontal intensity H = 9 a nT at a distance of a miles
from the pole.
Using these values, and the distance from Gjøahavn to the
estimated pole location (205 km where 1 mile = 1.852 km),
the equations were solved for a, so that the one-hour averaged values of the variation of H and D could be substituted
giving the variation in km of the location of the pole. The
variation of H yielded the north-south changes in the location of the pole and the variation of D yielded changes in the
east-west direction (Graarud and Russeltvedt, 1926).
The result of the calculation of the diurnal variation in pole
location is shown in Fig. 11, where the NMDP undergoes a
regular, diurnal drift caused mainly by ionospheric current
systems, created and driven by sunlight. These variations are
larger in summer than during the winter months, but the variations are biggest during very disturbed days. Thus, when
we today talk about the location of the pole, we are referring to an average position. The pole wanders daily in a
roughly elliptical path around this average position, and may
frequently be as much as 25 km away from this position during disturbed conditions. Figure 12 shows the rather smaller
annual variation of the location of the NMDP.
www.hist-geo-space-sci.net/2/99/2011/
28
607 608 Figure Twelve
A. Egeland and C. S. Deehr: Roald Amundsen’s
contributions to our knowledge
609 610 611 612 600 601 602 603 107
Figure 13a. Diurnal variation of the horizontal component at God-
604 605 Figure 12. The average annual location of the NMDP observed
from Gjøahavn for 1904 (from Graarud and Russeltvedt, 1926).
6
Solar wind, interplanetary magnetic field and
magnetic sector structures
Interplanetary space, not long ago believed to be empty of
matter, is filled with electrons and ions of solar origin. These
streaming particles carry with them the solar magnetic field
and are collectively called the solar wind. The presence of
the solar wind including the interplanetary magnetic field
(IMF) was verified as soon as in-situ measurements were carried out (Wilcox and Ness, 1965). Even if its amplitude is
only of the order of a few nT, it is an important field which
significantly influences disturbances on the Earth. The solar
wind together with the IMF is the connecting link between
solar activity and geophysical disturbances such as large variations in the Earth’s magnetic field and auroras. The 28- and
14-day variations observed are caused by solar particles and
are thus of special interest in relation to Amundsen’s field
measurements. Mainly due to the regular average 27.3 day
rotation of the Sun, the IMF is spiral-shaped. Near the Earth,
the field makes an angle of about 45◦ with the radial direction
(Egeland et al., 1973).
Solar observations accumulated over time indicated that
the polarity of the field is organized in a regular pattern. The
interplanetary sector structures were discovered during the
descending phase of sunspot cycle 19, with four stable sectors (Wilcox and Ness, 1965). The field was found to point
predominately outward from or inward toward the Sun for
about a week at a time and then change in a relatively short
time to the opposite polarity. This pattern was found to repeat, with only minor changes, for several rotations of the
Sun.
Both the two- and four-sectors – and more complicated
patterns, have been shown to be present at different epochs.
The two-sector pattern is consistent with the dipole field assumption. The four sector pattern implies a more compliwww.hist-geo-space-sci.net/2/99/2011/
havn during 1950. The curves labeled A and C are the average
variations on days classified as being of type A and of type C, respectively. In the interval, shown by the dashed lines, the largest
difference between the two types occurs (from Svalgaard, 1975).
cated solar magnetic field with a wavy neutral sheet (see
Sect. 7). The result is shorter intervals of unchanged polarity,
but with the same basic period of about 27 days (Egeland et
al., 1973; Kivelson and Russell, 1995).
7
Solar wind, interplanetary magnetic field and
magnetic sector structures 100 yr ago estimated
from Amundsen’s magnetic observations
The two main objectives of subjecting Amundsen’s
Gjøahavn data to modern analysis, are: firstly, to show it is
equal in quality and accuracy with those of the modern observatories of the late 20th century. Secondly, to learn about
the Sun and solar wind activity several decades before polar
region magnetic observatories were established. What follows are the Gjøahavn data showing the recently discovered
relationship of the high latitude variations of the local magnetic field to changes in the direction of IMF By and the solar
wind.
An objective method of inferring the polarity of the IMF
By component from high latitude magnetic observations was
developed by Svalgaard (1972). Named the SvalgaardMansurov Effect (Wilcox, 1972), this discovery led to the
development of a new method to infer the IMF direction
using the H-component observed at Godhavn (69◦ 150 N,
53◦ 320 W) after 1926 (Svalgaard, 1975). Because Godhavn
and Gjøahavn are at roughly the same magnetic latitude, but
separated by ∼3 h in longitude, we can subject the Gjøahavn
data to the same analysis that was carried out on the Godhavn data. Svalgaard plotted the variation of the one-hour averaged H-component from the monthly mean for 1950 from
Godhavn. Figure 13b shows the diurnal variations of the onehour averaged Gjøahavn H-component of June 1904 from
the monthly mean, for (1) all data (middle curve), (2) days
when a broad positive perturbation is observed between the
Hist. Geo Space Sci., 2, 99–112, 2011
108
613 614 615 616 30
Figure Thirteen b.
A. Egeland and C. S. Deehr: Roald Amundsen’s contributions to our knowledge
31
617 620 Figure
fourteen
Figure
13b.
Diurnal
variations of the H-component from the monthly mean at Gjøahavn for June 1904. The blue, red and yellow curves
618 621 are respectively
the average variations of the H-component on days with significant away from the Sun sector polarity (a broad positive
619 622 perturbation), the average value for the whole month and a toward the Sun polarity (i.e. a broad negative perturbation) intensities.
623 624 625 626 627 628 Figure 14. Deviation from the monthly mean of the Gjøahavn magnetic H-component for June, July and August 1904. The data are
averaged over the period when the Svalgaard-Mansurov effect is greatest between 12:00 and 18:00 UT each day at Gjøahavn. The days are
then assigned to appropriate solar Carrington rotations (CR) and the three CRs are superposed.
Hist. Geo Space Sci., 2, 99–112, 2011
www.hist-geo-space-sci.net/2/99/2011/
fteen a
636 Figure fifteen b.
637 contributions to our knowledge
A. Egeland and C. S. Deehr: Roald Amundsen’s
638 639 640 641 642 109
Figure 15b. Similar to Fig. 14a, but showing only the neutral sheet
to illustrate the distortion introduced by the departure of the solar magnetic equator from the solar spin equator and resulting in
four sector structure crossing per solar rotation as in CR 677–679,
observed from Gjøahavn (figure W. Heil, personal communication,
2011).
Figure 15a. A schematic three dimensional view of the solar magnetic field carried outward by the solar wind particles and its relationship to the Earth’s orbit in the ecliptic plane. Because the solar
spin pole is tilted with respect to the ecliptic plane, the solar magnetic field seen at Earth, changes direction twice each solar rotation,
changing from “away from the Sun” at point A to “toward the Sun”
at point C (modification of figure by Russell, 2001).
hours of 12:00 and 18:00 UT (upper curve: IMF away), and
(3) days when a broad negative perturbation in the field intensity is observed between the hours of 12:00 and 18:00 UT
(the lower curve: IMF toward). Figure 13a shows similar
data, but from Godhavn for 1950 (Svalgaard, 1975).
Taken together, Fig. 13a and b show the nature of both the
current systems that affect the diurnal curve of the magnetic
variation at stations in the polar cap such as these. Notice
that the curves of all of the data (middle curves) are of same
sinusoidal character reported by Wasserfall (1938). The difference between the two stations is that the sine waves are out
of phase. The reason for this is that the stations pass under
sunward-directed ionospheric currents going across the pole
that are fixed relative to the Sun, so that the stations pass
under the currents, at different Universal Times, resulting in
maxima and minima at different times.
It is apparent that we may use this effect on the Gjøahavn
H-component to infer the direction of the IMF By component as a function of time to ascertain the nature of the IMF
during 1904 (Svalgaard, 1975; Sandholt et al., 2002, p. 54).
To do this, we averaged the Gjøahavn H variation for the
period 12:00 to 18:00 UT for each day for May, June and
July of 1904, and plotted it as a function of time, superposing the three Carrington solar rotations. The result, shown
in Fig. 14, indicates that the IMF By component changed diwww.hist-geo-space-sci.net/2/99/2011/
rection four times each solar rotation during Carrington rotations 677, 678 and 679.
This picture of the interaction of the magnetosphere with
the solar wind is consistent with similar conditions today.
Note that the period of the Gjøahavn measurements, 1903–
1906, occurred just as solar activity peaked in solar cycle 14.
Indeed, the magnetospheric storm that occurred on 31 October 1903 was among the largest storms ever recorded (Cliver
and Svalgaard, 2004). Figure 15a shows the relationship of
the solar magnetic field, carried outward from the Sun by the
solar wind, to the Earth’s orbital plane. Because the solar
spin pole is tilted with respect to the ecliptic plane, the solar magnetic field seen at Earth, changes direction twice each
solar rotation when the solar magnetic field equator is undistorted and coincides roughly with the solar spin equator.
For solar activity levels indicated by the sunspot numbers
for the years 1903–1906, we would expect to see the solar magnetic equator distorted into a large sine wave on the
Sun. The resulting waves in the solar magnetic equatorial
plane introduce more interceptions of the Earth by the neutral
sheet with each solar rotation. Figure 15b shows the neutral
sheet forming a “ballerina skirt” that results when the solar
magnetic equator becomes significantly distorted, resulting
in four sector changes per solar rotation. Because each wave
results in two sector changes seen at Earth the number of
sector changes is usually even, although changes in the solar magnetic field can occur during one Carrington rotation
(CR), leading to an odd number of IMF By changes during
one rotation. It appears, however, that the four crossings during each of CR 677–679, seen in the Gjøahavn data (Fig. 14)
is consistent with the solar wind that we see today, 100 yr
later.
Hist. Geo Space Sci., 2, 99–112, 2011
644 645 646 110
A. Egeland and C. S. Deehr: Roald Amundsen’s contributions to our knowledge
647 648 649 650 651 652 653 654 35
Figure Seventeen a
Figure 16. Wasserfall’s exposition showing the monthly averaged diurnal variation in all three magnetic components from Gjøahavn for
1903–1904 (from Wasserfall, 1938).
655 656 657 658 659 Figure 17a. Wasserfall’s analysis of the diurnal variation of the
NMDP location averaged for July 1904, as seen from Gjøahavn
(figure from Wasserfall, 1938).
Hist. Geo Space Sci., 2, 99–112, 2011
8
Effect of the IMF on the diurnal variation of the
NMDP position
One of the most remarkable aspects of the high latitude magnetograms is the strikingly constant, large diurnal variation of
all the magnetic elements. Notice that it generally dominated
the traces in the Gjøahavn data, even during periods of auroral activity (Fig. 16). This led to the relatively smooth ellipse
found in the calculated diurnal variation of the pole position
from data for the entire year (Fig. 11). Wasserfall plotted
the July 1904 diurnal variation of the location of the NMDP
(Fig. 17a) and found a skewed distribution compared to the
regular ellipse shown in Fig. 11. Our plot of the diurnal variation of the location of the NMDP (Fig. 17b) shows the same
shape as Fig. 17a for all of the data from June 1904. When
we separated the days with IMF Toward and Away from the
Sun, we found that the main reason for the skewed distribution of the summer observations, relative to those from the
entire year (Fig. 11), was the overwhelming effect of the IMF
during that time.
9
Conclusions
We have shown that diurnal variations in the Earth’s magnetic field observed from Gjøahavn in 1904 are, in part,
associated with changes in the IMF By component through
the Svalgaard-Mansurov Effect. The magnitude of the effect,
and the character of the variations indicate that the solar
www.hist-geo-space-sci.net/2/99/2011/
36
660 Figure Seventeen b
661 A. Egeland
and C. S. Deehr: Roald Amundsen’s contributions to our knowledge
662 663 111
664 665 Figure 17b.
Showing the average diurnal variation of the NMDP location from the June 1904 Gjøahavn data for all days and for days with
666 and “away” from the Sun.
IMF “toward”
667 wind magnitude, direction and occurrence was similar to
that which we observe directly today. It is a testament to
the scientific abilities of Amundsen himself and his crew to
design and carry out the first continuous magnetic variation
recording inside the polar cap for a period of 19 months
under almost impossible conditions. In addition, the data set
is so well-calibrated and corrected, that, besides describing
the ordinary geomagnetic disturbances at a high latitude
station, we can infer the interplanetary magnetic field
structure and direction, for a time 60 yr before its discovery.
Edited by: K. Schlegel
Reviewed by: S. Silverman and M. Korte
References
Amundsen, R.: The Northwest Passage, Archibald Constable & Co.
Ltd., London, 1908a.
Amundsen, R.: The Northwest Passage, E. P. Dutton & Co., New
York, 1908b.
Brown, L. A.: The Story of Maps, Little, Brown & Son, New York,
1949.
www.hist-geo-space-sci.net/2/99/2011/
Campbell, W. H.: FORUM Comment on “Survey Track Current
Position of South Magnetic Pole” and “Recent Acceleration of
the North Magnetic Pole Linked to Magnetic Jerks”, Eos Trans.
AGU, 84, 42–43, 2003.
Chapman, S. C. and Bartels, J.: Geomagnetism, Clarendon, Oxford,
1940.
Cliver, E. W. and Svalgaard, L.: The 1859 solar-terrestrial disturbance and the current limits of extreme space weather activity,
Sol. Phys., 224, 407–422, 2004.
Egeland, A. and Burke, W.: Kristian Birkeland, The First Space
Scientist, Springer, Dordrecht, 2005.
Egeland, A. and Leer, E.: Professor Kr. Birkeland: His Life and
Work, IEEE T. Plasma Sci., 14, 666–678, 1973.
Egeland, A., Holter, O., and Omholt, A.: Cosmic Geophysics, Universitetsforlaget, Oslo, 1973.
Gilbert, W.: De Magnete, Peter Short, London, 1600 (1st edn., in
Latin).
Gilbert, W.: De Magnete, Basic Books, New York, 1958.
Good, G.: Follow the needle: seeking the magnetic poles, Earth Sci.
History, 10, 154–167, 1991.
Graarud, A. and Russeltvedt, N.: Die Erdmagnetischen Beobachtungen der Gjöa-Expedition 1903–1906, Geofys. Publ., III, 3–14,
1926.
Hist. Geo Space Sci., 2, 99–112, 2011
112
A. Egeland and C. S. Deehr: Roald Amundsen’s contributions to our knowledge
Huntford, R.: The Amundsen Photographs, Atlantic Monthly Press,
New York, 1987.
Kivelson, M. G. and Russell, C. T.: Introduction to Space Physics,
Cambridge University Press, Cambridge, 1995.
Kløver, G.: Cold Recall, The FRAM Museum, Oslo, 2009.
Korte, M. and Mandea, M.: Magnetic Poles and Dipole Variations,
Earth Planets Space, 60, 937–938, 2008.
Nippoldt, A.: Erdmagnetismus und Polarlicht, Einführung in die
Geophysik, 2, 1–168, 1929.
Ross, J. C.: On the position of the north magnetic pole, Trans. Phil.
Soc. Lon., 124, 47–51, 1834.
Russell, C. T.: Solar Wind and Interplanetary Magnetic Field: A
Tutorial, in: Space Weather, edited by: Song, P., Singer, H., and
Siscoe, G., Geophysical Monograph 125, American Geophysical
Union, Washington, DC, 2001.
Sandholt, P. E., Carlson, H., and Egeland, A.: Dayside and Polar
Cap Aurora, Kluwer Academic Publ., 2002.
Schrøder, W., Wiederkehr, K. H., and Schlegel, K.: Georg von Neumayer and geomagnetic research, Hist. Geo. Space Sci., 1, 77–
87, 2010.
Scott, R. F.: The Voyage of the Discovery: Scott’s first Antartic
Expedition, Harrison and Sons, LTD, London, 1906.
Silverman, S. M. and Smith, M. E.: Amundsen and Edmonds: Entrepreneurial and Institutional Exploration, in: The Earth the
Heavens and the Carnegie Institution of Washington, American
Geophysical Union, Washington D.C., 69–79, 1994.
Steen, A. S., Russeltvedt, N., and Wasserfall, K. F.: The Scientific
Results of the Norwegian Arctic Expedition in the Gjøa 1903–
1906 under the conduct of Roald Amundsen. Part III, Terrestrial
Magnetism Photgrams, Geofys. Publ., Vol. VIII, No. 1, 1–17,
1930.
Hist. Geo Space Sci., 2, 99–112, 2011
Steen, A. S., Russeltvedt, N., and Wasserfall, K. F.: The Scientific
Results of the Norwegian Arctic Expedition in the Gjøa 1903–
1906 under the conduct of Roald Amundsen. Part II. Terrestrial
Magnetism, Geofys. Publ., Vol. VII, No. 1, 1–309, 1933.
Svalgaard, L.: Interplanetary magnetic-sector structure 1926–1971,
J. Geophys. Res., 77, 4027–4034, 1972.
Svalgaard, L.: On the Use of Godhavn H Component as an Indicator
of the Interplanetary Sector Polarity, J. Geophys. Res., 80, 2717–
2722, 1975.
Wasserfall, K. F.: On periodic variations in terrestrial magnetism,
Geofys. Publ., Vol. V, No. 3, 3–33, 1927.
Wasserfall, K. F.: On the diurnal variation of the magnetic pole,
Terr. Magn., 43, 219–225, 1938.
Wasserfall, K. F.: Studies on the magnetic conditions in the region
between Gjoahavn and the magnetic pole during the year 1904,
Terr. Magn., 44, 263–275, 1939.
Wilcox, J.: Inferring the Interplanetary Magnetic Field by Observing the Polar Geomagnetic Field, Rev. Geophys. Space Ge., 10,
1003–1014, 1972.
Wilcox, J. and Ness, N. F.: Quasi-stationary Corotating Structure in the Interplanetary Medium, J. Geophys. Res., 70, 5793,
doi:10.1029/JZ070i023p05793, 1965.
Zhang, Y., Sun, W., Feng, X. S., Deehr, C. S., Fry, C. D., and Dryer,
M.: Statistical analysis of corotating interaction regions and their
geoeffectiveness during solar cycle 23, J. Geophys. Res., 113,
A08106, doi:10.1029/2008JA013095, 2008.
www.hist-geo-space-sci.net/2/99/2011/